Download Les circuits électriques

Name: ____________________________________________
Group: __________
Support activities – Second Year of Secondary Cycle Two
ACTIVITY 22
ANSWER KEY
Date: __________________
EST
STUDENT BOOK: Chapter 5, pages 156–163
RELATED HANDOUT: Concept review 22
Electrical circuits
1. Complete the following sentences, using the words or groups of words in the box below. You
may use some words more than once.
•
•
•
•
•
•
•
•
adds up
branch out
charges
circuit
circuit breakers
conservation of charge
conservation of energy
continues to flow
•
•
•
•
•
•
•
•
conventional
current
current intensity
diagrams
electrical energy
equal to
equivalent resistance
flow
•
•
•
•
•
•
•
•
motion
negative
node
parallel
positive
potential
power supply
reduces
•
•
•
•
•
•
•
•
resistors
series
shared
single
total energy acquired
total energy transferred
value
wires
flow
a) For charges to ________________________
, they must be able to move in a loop like a
racetrack. A circuit provides them with a loop to flow through, and a power supply keeps
motion
circuit
them in ________________________
. Any ________________________
must contain at
power supply
least the following three components: a ________________________
to create a potential
electrical energy
difference, one or more elements that use _______________________
(for example, a light
© ERPI Reproduction and adaptation permitted
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wires
bulb), and ________________________
that connect the elements and the power supply.
diagrams
b) Symbols and ________________________
are often used to represent electrical circuits.
conventional
The current is shown in the ________________________
current direction, in other words,
positive
negative
from the _______________________
terminal to the _______________________
terminal.
Series
parallel
c) ________________________
circuits and ________________________
circuits are two
ways of connecting the components of an electrical circuit.
series
d) In a ____________________
circuit, the components are connected end to end. The circuit
branch out
does not ____________________
, which means that all the charges follow the same path.
current
If one of the circuit components is defective, the ______________________
ceases to flow.
adds up
The energy used by each of the resistors ______________________
. Adding resistors
reduces
_____________________
the energy available for each one. Fuses and
series
circuit breakers
____________________
are examples of elements connected in ____________________
.
Observatory / Guide
11129-B
1
ANSWER KEY
Support activities – SecondYear of Secondary Cycle Two
ACTIVITY 22
Electrical circuits
Name: ____________________________________________
Group: __________
Date: __________________
parallel
e) A________________________
circuit branches out in at least one place. The
charges
________________________
can therefore take different paths. The point at which a circuit
node
separates into two paths is called a “________________________
.” If an element of the
continues to flow
circuit is defective, the current ________________________
through the elements in the
reduces
other branches. Adding resistors ________________________
the total resistance. The
shared
current intensity is ________________________
among the various resistors.
f)
EST Two important laws in electricity are based on the law of
conservation of charge
_______________________
conservation of energy
and the law of ________________________
. Kirchhoff’s first law states that the
current intensity
________________________
flowing into an element or a node of an electrical circuit is
equal to
always ________________________
the current intensity flowing out of it. Kirchhoff’s
total energy acquired
second law is about potential difference. It states that the ________________________
by
total energy transferred
the charges from the power supply is always equal to the ________________________
by
these charges, whatever pathway they may take in the circuit.
series
g) EST Kirchhoff’s two laws can be summarized as follows: In a _______________________
circuit, the total current intensity is equal to the current that flows through each of the
resistors
________________________
, and the total potential difference is equal to the sum of the
parallel
potential differences of all the resistors in the circuit. In a ________________________
circuit, the total intensity is equal to the sum of the currents flowing through each of the
potential
resistors in the circuit, and the total ________________________
difference is the same
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solely for classroom use with Observatory.
everywhere, for each element in the circuit.
h) EST The following equations represent Kirchhoff’s two laws:
series
For a ________________________
circuit: Itotal  I1  I2  I3  I4  …
Vtotal  V1 + V2 + V3 + V4 + …
parallel
For a ________________________
circuit: Itotal  I1 + I2 + I3 + I4 + …
Vtotal  V1  V2  V3  V4  …
i)
equivalent resistance
, symbolized by the letters Req, is equal
EST The ________________________
to the resistance value needed to replace all the resistors in a circuit with a
single
________________________
resistor. By applying Ohm’s law and Kirchhoff’s laws, this
value
________________________
can be calculated with the following equations:
Observatory / Guide
11129-B
2
ANSWER KEY
Support activities – SecondYear of Secondary Cycle Two
ACTIVITY 22
Electrical circuits
Name: ____________________________________________
Group: __________
Date: __________________
series
For a ________________________
circuit: Req  R1 + R2 + R3 + R4 + …
1
parallel
For a ________________________
circuit: Req =
1
1
1
+
+
+…
R1
R2 R3
2. Draw a series circuit and a parallel circuit that each include a power supply, two light bulbs and
two resistors.
Answers will vary. Examples:
a) series circuit
b) parallel circuit
3. Calculate the resistance value in the circuit below.
In a series circuit,
V = RI
V
I
100 V
R=
2A
R = 50 Ω
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solely for classroom use with Observatory.
R=
4. EST Calculate the current intensity flowing through the R1 resistor in the circuit below.
In a series circuit, the current intensity is the same everywhere. Consequently, R1 = 10 A.
Observatory / Guide
11129-B
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ANSWER KEY
Support activities – SecondYear of Secondary Cycle Two
ACTIVITY 22
Electrical circuits
Name: ____________________________________________
Group: __________
Date: __________________
5. EST In the circuit below, what is the potential difference at the terminals of the power supply?
In a parallel circuit, the potential difference is the same everywhere. At the power supply terminals, it
y différence
deV.
potentiel est égale partout. Aux bornes de la source, elle
isalso
therefore
also 80
6. EST In the table below, write the equations that express the application of Ohm’s law and
Kirchhoff’s laws to series and parallel circuits.
Characteristic
Current intensity
Potential difference
Equivalent resistance
Series circuit
Parallel circuit
Itotal = I1 = I2 = I3 = I4 = …
Itotal = I1 + I2 + I3 + I4 + …
Vtotal = V1 + V2 + V3 + V4 + …
Vtotal = V1 = V2 = V3 = V4 = …
1
Req = R1 + R2 + R3 + R4 + …
Req =
1
1
1
+
+
+…
R3
R2
R1
7. EST Calculate the equivalent resistance in each of the following three circuits.
© ERPI Reproduction and adaptation permitted
solely for classroom use with Observatory.
a)
Series circuit:
Req = R1 + R2 + R3
= 100 Ω + 50 Ω + 30 Ω
= 180 Ω
Parallel circuit:
Req =
b)
Req =
1
1
1
+
R1
R2
1
1
1
+
50 Ω
50 Ω
Req = 25 Ω
Observatory / Guide
11129-B
4
ANSWER KEY
Support activities – SecondYear of Secondary Cycle Two
ACTIVITY 22
Electrical circuits
Name: ____________________________________________
Group: __________
Date: __________________
c)
Parallel circuit:
Req =
Req =
1
1
1
1
+
+
R1
R2
R3
1
1
1
1
+
+
100 Ω
25 Ω
75 Ω
© ERPI Reproduction and adaptation permitted
solely for classroom use with Observatory.
Req = 15.78 Ω
Observatory / Guide
11129-B
5
ANSWER KEY
Support activities – SecondYear of Secondary Cycle Two
ACTIVITY 22
Electrical circuits